1. Field of the Invention
This invention relates to a film jacket for flat articles, particularly slide frames, which jacket consists of top and bottom film plies, which are joined at one end and on both side edges so that they are adapted to receive the slide frames.
2. Description of the Prior Art
Such a film jacket is generally known in practice. The known film jacket consists of top and bottom film plies and has the configuration of an elongate rectangle. The two longitudinal sides of the superposed film plies are joined to each other. The two film plies are also joined at one end but are unconnected at the opposite end, where a receiving opening is provided, through which the slide frames can slidably be inserted into the tubular film, which is constituted by the two film plies and is closed at one end. The tubular film is somewhat wider than the flat slide frames which are to be slidably inserted. The slide frames are inserted successively or one behind the other into the known film jacket. A slide frame cannot be removed from the known film jacket in a simple manner unless the slide frame is nearest to the opening. When a succeeding slide frame is to be removed for a viewing of the slide, those slide frames which are nearer to the opening than the desired slide frame must be removed before so that for an access to the desired slide frame it may be necessary, in the least favorable case, to remove also all other slide frames from the film jacket if the slide frame to be taken is the rearmost one disposed at the closed end of the tubular film. It is apparent that the known film jacket does not permit a simple direct access to each of the slide frames which are kept in the jacket.
In another known system for keeping frames which is known in practice, a plurality of juxtaposed film pockets are provided, which are welded on a continuous bottom film ply. The bottom film ply and the top film ply sections which constitute the pockets may be joined by embossed portions. The system described last permits of a simple and quick access to each of the slide frames which are in storage. But that system has the disadvantage that it can be filled only in a complicated operation. The slides are usually mounted by machine. When the slide frames have thus been completed they must be inserted into a film jacket. It will be of advantage to insert a plurality of complete slide frames into the film jacket through a single opening therein. That operation cannot be performed with the system described last because a separate pocket having a separate opening is provided for each complete slide frame.
Another system that is known in practice has a separate pocket with a separate opening for each slide frame. To make the film jacket, a single ply is folded in Z-shape and transverse seam welds are then formed in a direction which is transverse to the folds of the Z-shaped ply. Those transverse seam welds have a spacing which slightly exceeds the width of a slide frame. The separate pockets for keeping respective slide frames are thus formed by the combination of the ply that is folded in Z shape and the transverse seam welds. That system has the same disadvantages as the one which has been described hereinbefore.